When is it acceptable to log at the Warn or Info level?

Logging at the Warn or Info level is appropriate when an exception is expected because it indicates a non-critical situation that does not disrupt the flow of the application but still warrants attention. This type of logging helps developers and system administrators understand that while something unusual has occurred, it is part of the expected behavior of the application under certain conditions.

For instance, if a particular input condition is known to sometimes raise a non-fatal error, logging a warning allows teams to be aware of it without assuming something has gone wrong. Using the Warn level for this purpose enables the documentation of these conditions systematically, allowing for better monitoring and troubleshooting while not overwhelming log files with excessive data.

In contrast, using the Warn or Info levels incorrectly, such as for all debug messages (which generally belong at the Debug level), or in scenarios where the application's performance is critical, could lead to cluttered logs that obscure genuinely important information. Logging during an unstable state of the application could also mislead the analysis of the system's health and operational status.